This invention relates to planographic printing and provides a planographic printing member precursor, a method of preparing a planographic printing member and such a printing member per se.
Planographic and/or lithographic processes involve establishing image (printing) and non-image (non-printing) areas on a substrate, substantially on a common plane. When such processes are used in printing industries, non-image areas and image areas are arranged to have different affinities for printing ink. For example, non-image areas may be generally hydrophilic or oleophobic and image areas may be oleophilic. In xe2x80x9cwetxe2x80x9d lithographic printing, a dampening or fountain (water-based) liquid is applied initially to a plate prior to application of ink so that it adheres to the non-image areas and repels oil based inks therefrom. In xe2x80x9cdryxe2x80x9d printing, ink is repelled from non-image areas due to their release property.
There are numerous known processes for creating image and non-image areas. Some processes rely on the differential solubility of exposed and non-exposed areas in a developer; others use incident radiation to break covalent bonds of radiation sensitive formulations or to ablate a layer of material.
It is an object of the present invention to provide a novel planographic printing member precursor and/or method of preparing the same and/or method of preparing a printing member and/or such a printing member per se.
According to the present invention, there is provided a planographic printing member precursor comprising a first component and a second component, said first and second components being arranged to interact in areas exposed to imaging radiation for providing a surface having a first affinity for ink and one of either said first or second components being removable in non-exposed areas for providing a surface having a second affinity for ink different to said first affinity.
Suitably, only one of either said first or second components is removable in non-exposed areas. Preferably, said surface having a second affinity for ink is arranged to be defined, at least in part, by said first or second component which is not removable in non-exposed areas.
Said surface having a first affinity for ink is preferably relatively hydrophilic and/or oleophobic. Said surface having a second affinity for ink is preferably relatively oleophilic.
Said first and second components preferably include respective first and second functional groups or precursors thereof which are arranged to interact, especially to react, with one another for the formation of covalent bonds between the first and second components. Preferably, prior to said interaction said first and second components are not covalently bonded to one another. Thus, imaging radiation suitably does not break any covalent bonds between said first and second components.
Preferably, said first component includes a functional group or a functional group precursor capable of undergoing a condensation reaction with a functional group of said second component. The term xe2x80x9cfunctional group precursorxe2x80x9d includes a reference to a functional group which can be converted to another group or moiety in situ which can react as described. Said first component preferably includes one or more hydroxy groups. Said first component preferably comprises a polymer having hydroxy groups. Said polymer may comprise an inorganic polymer, for example a glass or an organic polymer for example a resin such as a phenolic resin and/or a resole resin and/or an epoxy resin and/or a hydroxypropylcellulose and/or a polyvinyl butyral and/or a polyvinyl alcohol.
Said first component preferably includes an oleophilic and/or hydrophobic moiety. It is preferably oleophilic and/or hydrophobic when in isolation.
Said second component may include a functional group or functional group precursor capable of undergoing a condensation reaction with a functional group, especially a hydroxy group, of said first component. Said functional group or precursor preferably includes a moiety xe2x80x94Oxe2x80x94; it may be an hydroxy or an optionally-substituted alkoxy group. When it is an alkoxy group, the group may suitably represent a functional group precursor which may undergo an initial transformation prior to said condensation reaction.
Said second component preferably includes a hydrophilic and/or oleophobic moiety.
Said second component may comprise an optionally-substituted siloxane or, preferably, is of general formula 
wherein M represents a silicon or a titanium atom and each of R1, R2, R3 and R4 is independently selected from hydrogen or halogen atoms; a hydroxy group; an optionally-substituted alkyl, alkenyl or alkynyl group; an optionally-substituted alkoxy group; or an optionally-substituted saturated or unsaturated cyclic or heterocyclic group.
Unless otherwise stated in this specification, an alkyl, alkenyl or alkynyl group may have up to 20, suitably up to 10, preferably up to 8, more preferably up to 6, especially up to 4 carbon atoms with methyl, ethyl, propyl and vinyl groups being preferred; an alkoxy group may have up to 10, suitably up to 8, preferably up to 6, more preferably up to 4 carbon atoms; a saturated or unsaturated cyclic group may have up to 12, suitably up to 10, preferably up to 8, more preferably up to 6, carbon atoms and includes an aromatic group. A heterocyclic group may have 5 or 6 ring atoms.
Unless otherwise stated, where any group is stated to be xe2x80x9coptionally-substitutedxe2x80x9d in this specification, it may be substituted by one or more: halogen atoms, especially fluorine, chlorine or bromine atoms; hydroxy or cyano groups; carboxyl groups or carboxy derivatives, for example carboxylic acid salts; and optionally-substituted alkyl, alkenyl, alkynyl, alkoxy, amino, sulphinyl, sulphonyl, sulphonate and carbonyl groups.
At least two, preferably at least three, of R1, R2, R3 and R4 includes a moiety xe2x80x94Oxe2x80x94 bonded to atom M.
Preferably, R1 represents a hydroxy group or an optionally-substituted, especially an unsubstituted, alkoxy group.
R2 may represent a hydroxy group or an optionally-substituted alkoxy, alkyl, alkenyl, cycloalkyl or phenyl group. Preferably, R2 represents a hydroxy group or an optionally-substituted, especially an unsubstituted, alkoxy group.
R3 may represent a hydroxy group or an optionally-substituted alkoxy, alkyl, alkenyl, cycloalkyl or phenyl group. R3 preferably represents a hydroxy group or an optionally-substituted alkoxy group. A preferred optionally-substituted alkoxy group may include a saturated or unsaturated carbon chain and may be substituted by a group xe2x80x94COOQ, where Q represents an optionally-substituted, especially an unsubstituted, alkyl group or a cationic group, especially a group NH4+.
R4 may represent a group which confers hydrophilicity and/or oleophobicity on said second component. R4 may represent an optionally-substituted alkoxy, alkyl, alkenyl, cycloalkyl or phenyl group. A preferred optionally-substituted alkoxy group may be as described above for group R3. A preferred optionally-substituted alkyl group is substituted by a group xe2x80x94S(O)x(OH)y where x and y independently represent 0, 1, 2 or 3 provided that x+y=3. Preferably, y represents 1. R4 preferably represents an optionally-substituted alkoxy or alkyl group.
Where M represents a titanium atom, R1 and R2 preferably represent hydroxy groups and R3 and R4 preferably represent alkoxy groups substituted by a group xe2x80x94COOQ as described above.
Where M represents a silicon atom, R1, R2 and R3 may be the same or different, preferably the same, and may represent a hydroxy group or an optionally-substituted, especially an unsubstituted, alkyl group. R4 preferably represents an optionally-substituted alkyl group. In one class of compounds, R4 may represent an alkyl group substituted by a group xe2x80x94S(O)x(OH)y as described above. In another class of compounds, R4 may represent an alkyl group substituted by a group Rf xe2x80x94(Y)mxe2x80x94(X)nxe2x80x94 wherein X represents xe2x80x94NR5xe2x80x94 wherein R5 represents a hydrogen atom or an optionally-substituted, especially an unsubstituted, alkyl group; n represents 0 or 1; Y represents an oxygen atom or a sulphinyl, sulphonyl or carbonyl group; m represents 0 or 1; and Rf represents a fluoroaliphatic group, suitably having 3 to 10 carbon atoms.
A preferred compound of general formula I where M represents a titanium atom is 
Compounds of general formula I which include a silicon atom and which fall within the scope of the present invention include chloromethylmethylsilanediol, methylvinylsilanediol, dichloromethyldimethylsilanol, chloromethyldimethylsilanol, ethylmethylsilanediol, ethoxymethylsilanediol, dimethoxymethylsilanol, trimethylsilanol, divinylsilanediol, methyl-3,3,3-trifluoropropylsilanediol, allylmethylsilanediol, dimethylvinylsilanol, 3-chloropropylmethylsilanediol, diethylsilanediol, methylpropylsilanediol, diethoxysilanediol, 3-cyanopropylmethylsilanediol, allyldimethylsilanol, 3-chloropropyldimethylsilanol, butylmethylsilanediol, dimethylpropylsilanol, dimethylisopropylsilanol, diphenylsilanediol, diallylsilanediol, 3-cyanopropyldi methylsilanol, methylpentylsilanediol, triethylsilanol, tert-butyldimethylsilanol, tri-ethoxysilanol, methylphenylsilanediol, dimethylphenylsilanol, cyclohexylmethylsilanediol, hexylmethylsilanediol, phenylvinylsilanediol, 6-methyldihydroxysilyl-2-norbornene, 2-methyldihydroxysilylnorbornene, 3-methacryloxypropylmethylsilanediol, heptylmethylsilanediol, dibutylsilanediol, allylphenylsilanediol, methylphenylvinylsilanol, 3-chloropropylphenylsilanediol, methy-xcex2-phenethylsilanediol, benzyldimethylsilanol, 2-(4-cyclohexenylethyl)methylsilanediol, methyloctylsilanediol, tripropylsilanol, tert-butylphenylsilanediol, dimethyloctylsilanol, decylmethylsilanediol, methyldiphenylsilanol, dihexylsilanediol, tributylsilanol, diphenylmethylsilanol, dodecylmethylsilanediol, diphenylvinylsilanol, trihexylsilanol, methyloctadecylsilanediol, dimethyloctadecylsilanol, tribenzysilanol, docosylmethylsilanediol, 1,2-bis(methyldihydroxysilyl)ethane, 1,1,3,3-tetramethyl-1,3-dihydroxysiloxane, 1,2-bis(dimethylhydroxysilyl)ethane, 1,4-bis(dimethylhydoxysilyl)benzene, 1,3-dihydroxytetraisopropyldisiloxane, cis-(1,3,5,7-tetrahydroxy)-1,3,5,7-tetraphenylcyclotetrasiloxane, etc. Among them preferable ones are diphenylsilanediol, triphenylsilanol, and cis-(1,3,5,7-tetrahydroxy)-1,3,5,7-tetraphenylcyclotetrasiloxane.
Preferred compounds of general formula I which include a silicon atom include 
The interaction, especially the reaction, of said first and second components in exposed areas may be aided, for example by being catalysed, by a catalytic component associated with the printing member precursor. Said catalytic component may be associated with said first and/or said second components but is preferably associated with said second component. Said catalytic component or a precursor thereof may be provided by a third component which may be in intimate contact with said second component, for example by said second and third components being provided in the same layer of said precursor.
Said third component is preferably an active hydrogen compound.
Said third component may be selected from triazine, diazonium, iodonium, sulphonium, phosphonium, selenonium and arsonium compounds and salts of fluorophosphoric acid.
Preferred triazine compounds are of general formula: 
wherein R10 represents an optionally-substituted aliphatic or aromatic group and R11 and R12 independently represent a haloalkyl group. An especially preferred triazine compound is 2-(4-methylthiophenyl)-4,6-trichloromethyl-S-triazine.
A preferred diazonium compound is a diazo salt, for example 4-diazodiphenylamine hexafluorophosphate. A preferred iodonium compound is diphenyliodonium iodide. A preferred sulphonium compound is an amine salt of p-toluene sulphonic acid.
Preferably, said third component is a triazine, diazonium or sulphonium compound.
Said third component may be a Lewis acid.
Said third component may be arranged to be decomposed in areas of said precursor exposed to radiation. Said third component may be decomposable on exposure to UV and/or visible and/or IR radiation and/or heat.
In some embodiments, for example when using triazines, it is believed that a said third component may decompose and generate an acid in exposed areas which can catalyse a reaction of the first and second components. Thus, in this case, said third component may be an acid generator.
Said printing member precursor may include a component for sensitising the precursor to imaging radiation, for example to infra-red, ultra-violet or visible radiation. Sensitisation suitably involves the component absorbing imaging radiation and preferably converting it to heat. Said component for sensitising may comprise said third component described above, in which case, said third component may have a dual role. Alternatively, and/or additionally, said component for sensitising may comprise a fourth component.
Where the fourth component is for sensitising to infra-red radiation, it may comprise a black body absorber such as carbon black or graphite or a commercially available pigment such as Heliogen Green as supplied by BASF, nigrosine base NGl as supplied by NH Laboratories Inc, or Milori Blue as supplied by Aldrich; or a metal such as iron, copper, aluminium or platinum; or an organic pigment or dye such as phthalocyamine pigment or a dye or pigment of the squarylium, merocyanine, cyanine, indoliane, pyrylium or metal dithioline classes. Metals may be present as small particles, especially in the case of iron and copper, or as a film layer, especially in the case of aluminium or platinum.
Where the fourth component is for sensitising to ultraviolet radiation, it may comprise a triazine compound as described above.
Where the fourth component is for sensitising to visible radiation, it may be a titanocene compound or a ketocoumarin compound which absorbs visible radiation.
Preferably, said fourth component is in intimate contact with said first and/or said second components. Said fourth component may be provided in a layer which includes said first component or in a layer which includes said second component or in a layer which includes both said first and second components or in both a layer which includes said first component and a separate layer which includes said second component.
Said printing member suitably includes a support.
Said support may comprise a metal layer. Preferred metals include aluminium, zinc and titanium, with aluminium being especially preferred. Said support may comprise an alloy of the aforesaid metals. Other alloys that may be used include brass and steel, for example stainless steel.
Said support may comprise a non-metal layer. Preferred non-metal layers include layers of plastics, paper or the like. Preferred plastics include polyester, especially polyethylene terephthlate.
Especially preferred supports include aluminium and plastics materials.
Said support may be any type of support used in printing. For example, it may comprise a cylinder or, preferably, a plate. Said support may have a width of at least 10 cm, suitably at least 20 cm, preferably at least 30 cm, more preferably at least 40 cm, especially at least 50 cm. Said support may have a width of less than 300 cm, suitably less than 200 cm, preferably less than 160 cm, more preferably less than 100 cm, especially less than 80 cm.
Said support may have a length of at least 20 cm, suitably at least 40 cm, preferably at least 60 cm. Said support may have a length of less than 300 cm, suitably less than 250 cm, preferably less than 200 cm, more preferably less than 150 cm, especially less than 105 cm.
Said support may have a thickness of at least 0.1 mm. Said support may have a thickness of less than 0.6 mm.
Preferably, said first or second component which is removable is present in an outermost layer of the printing member precursor. The other one of said first or second components may be present in the same layer as the component which is removable or may be present in an underlying layer which is preferably in contact with the layer in which the removable component is present.
Preferably, said second component is removable in non-exposed areas.
Said printing member precursor may comprise a first layer which includes said second component. Said first layer may also include said first component. Alternatively and/or additionally, said precursor may include a second layer which may include said first component and, preferably, said first and second layers are in intimate contact. Said fourth component may be present in said first layer and/or said second layer and/or a third layer which suitably underlies said first and/or said second layers. A preferred form of third layer is a thin metal film layer.
Said printing member precursor may comprise a said support, optionally a said third layer over the support, optionally a said second layer over the third layer, and a said first layer over the second layer and/or third layer (when provided).
Said printing member precursor may be for use in wet or dry (waterless) printing. For example, wherein said first affinity represents a hydrophilic state, said precursor may be for use in wet printing and wherein said first affinity represents an oleophobic state, said precursor may be for use in dry printing.
According to a second aspect of the present invention, there is provided a method of preparing a planographic printing member precursor, the method comprising associating a first component with a second component, suitably over a support, said first and second components being arranged to interact in areas exposed to imaging radiation for providing a surface having a first affinity for ink and one of either said first or second components being removable in non-exposed areas for providing a surface having a second affinity for ink different to said first affinity.
According to a third aspect of the present invention, there is provided a method of preparing a planographic printing member including the step of imagewise exposing a planographic printing member precursor according to said first aspect to imaging radiation.
Imaging radiation as described may comprise visible, ultra-violet or infra-red radiation or direct (e.g. conducted) heat. Radiation may be supplied by any known means, for example, imaging radiation in the form of heat may be supplied using a heated body, for example a heated stylus. Alternatively, said radiation may be supplied using a laser for example which suitably emits in the near-IR region between 700 and 1500 nm.
Imaging radiation may be applied directly to the precursor or may be applied indirectly using a mask.
Where the precursor includes a component for sensitising, for example a fourth component as described, said component may absorb imaging radiation and make the absorbed energy available for subsequent steps. Alternatively, said third component may itself absorb imaging radiation. The absorbed energy may be arranged to activate a catalytic effect of the third component on the interaction of the first and second components. For example, absorbed energy may cause the third component to generate an acid which may catalyse a reaction of the first and/or second components. In one embodiment, where said second component includes one or more optionally-substituted alkoxy groups, the third component may generate an acid which catalyses the hydrolysis of the alkoxy group(s), thereby facilitating reaction of the first and second components.
The method may include an optional step of blanket heating of the precursor after imagewise exposure. Such blanket heating may be arranged to facilitate the formation of covalent bonds in exposed areas. Said blanket heating may involve heating, in a conventional heating oven, to over 100xc2x0 C., preferably over 120xc2x0 C., more preferably 130xc2x0 C. or over for at least 30 seconds, preferably at least one minute, more preferably at least two minutes, especially three minutes or more.
The method may include the step of removing one of either the first or second components in non-exposed areas. Removal may include developing the exposed precursor using physical and/or chemical means. Physical means may include the use of a roller (or the like), especially a roller used to apply fluid, especially ink, to the member during printing. Chemical means may involve use of a fluid. For example, printing ink may be used or, alternatively, a separate developing fluid may be used such as water or a silicate-based developing formulation. It will be appreciated that the precursor may be developed on press and this is preferred.
Said method may be for preparing a planographic printing member for use in wet or dry (waterless) printing.
According to a fourth aspect of the invention, there is provided a planographic printing member having printing and non-printing areas prepared in a method according to the second aspect.
Any feature of any aspect of any invention or embodiment described herein may be combined with any feature of any aspect of any other invention or embodiment described herein.
Specific embodiments of the invention will now be described, by way of example.
The following products are referred to hereinafter:
BKR 2620xe2x80x94a phenol-formaldehyde-cresol resin obtained from Georgia-Pacific Resins Inc, U.S.A.
Degussa FW1xe2x80x94a channel-type carbon black obtained from Degussa of Macclesfield, U.K.
Si 285xe2x80x943-(Trihydroxysilyl)-1-propanesulphonic acid obtained from Degussa of Macclesfield; U.K.
Nacure 2530xe2x80x94Amine salt of p-toluene sulphonic acid obtained from K and K Greeff Ltd of England.
Luconyl Black 0066xe2x80x9440 wt % of carbon black in water/butyl glycol supplied by BASF Plc, Cheshire, England.
Tyzor LAxe2x80x94Dihydroxy-bis-diammonium-2-hydroxy-propanato (2)-titanate (50 wt %) in water (50 wt %) obtained from MDA Chemicals Ltd, Lancaster, England.
Novolac resin LB744xe2x80x94a cresol-novolac resin supplied Bakelite.
Silyl ether A solutionxe2x80x94a 60 wt % solution in ethanol of the following obtained from 3M Industrial Chemical Division, Minnesota, U.S. (a developmental material No. L12833). 
Silyl ether B solutionxe2x80x94a 60 wt % solution in ethanol of the following obtained from Fluorochem, Glossop , U.K. 
Silyl ether C solutionxe2x80x94a 60 wt % solution in ethanol of the following obtained from Fluorochem, Glossop, U.K. 
Epikote 1004 resinxe2x80x94a bis-phenol A epichloneohydrin resin supplied by Astor Stag Ltd of Middlesex, England.
DS019xe2x80x94a 4-diazonium diphenylamine paratoluene sulphonate formaldehyde condensate for acid generation, supplied by PCAS, Longjumeau, France.
IR Sensitizer Ixe2x80x94Catalogue No. i-I-8xe2x80x94an IR absorbing dye, as shown below, supplied by H W Sands of Florida, U.S.A. 
LDN1PF6 formulationxe2x80x9410 wt % of a 4-diazonium diphenylamine formaldehyde condensate hexafluorophosphate salt in DMF supplied by Varichem Ltd of Brynmawr, Wales.
Creo Trendsetterxe2x80x94refers to a Creo Trendsetter 3244 using Procomm Plus software, operating at a wavelength of 830 nm at powers of up to 8 W and supplied by Creo Products Inc, Burnaby, Canada.